1. Field of the Invention
This invention relates to communication. Specifically, the present invention relates to network testing and measurement.
2. Description of the Prior Art
Maintaining a communication network includes monitoring the network. The network is often monitored for a variety of factors. For example, the network may be monitored for performance, network outages, etc.
Federal regulations require that service provider network outages are accurately logged and communicated to federal agencies. Failure to do so may affect the service provider adversely. Failures in a SONET network are measured in Minutes of Outage (MOO). To gain accurate and precise MOO(s) a variety of factors have to be considered. For example, there are typically a large number of optical facilities such as OC48 facilities in a network. Each OC48 facility may be part of a facility hierarchy. For example, a higher-level OC48 facility may include lower-level facilities, such as OC1(s), T3(s), T1(s), etc. In conventional systems when a level in the hierarchy fails, a single outage may be counted more than once for the same failure. For example, several levels in the hierarchy may be counted and each level may be counted more than once.
Referring to FIG. 1, if a failure is detected on a lower-level facility as well as on the uppermost OC48 facility, it should not be counted twice towards MOO, since the failure of the lower-level facility will already be counted as part of the higher-level OC48 outage. Also, MOO should not be counted if any SONET facility is scheduled for planned maintenance. Double counting and counting planned maintenance can result in inaccurate MOO calculations. As a result, incorrect MOO values may be communicated to federal authorities. This could result in penalties for a service provider.
In FIG. 1, time in increments of 5 seconds is shown on the x-axis beginning with 11:00 and ending with 13:00. Each vertical bar is defined as a five-minute interval. A facility hierarchy is shown on the y-axis. The facility hierarchy includes T33, OC12, OC11 and OC48. Lastly, planned maintenance (PM) is shown on the y-axis.
In FIG. 1, a set of alarms on different levels of the same OC48 hierarchy is shown. As shown, “alarm_11” for the OC48 failed at 11:00 and was restored at 11:20. The “alarm_12” for the OC1, failed at 11:15 and was restored at 11:25. Using conventional methods, “alarm_12” would count for 20 minutes in the MOO calculation and “alarm_12” would count for 10 minutes in the MOO calculation. However, since the failure on the OC48 (i.e., alarm_11), which is a higher-level facility, overlaps with the failure on the OC1 (i.e., alarm_12), which is a lower-level facility, the first five minutes of “alarm_12” should not be counted toward the MOO calculation. However, in conventional systems, the overlap is counted twice (i.e., double counted).
Thus, there is a need for a method of accurately calculating MOO in facility hierarchies.